Project description:Reactive astrocytes are typically studied in models that cause irreversible mechanical damage to axons, neuronal cell bodies, and glia. We evaluated the response of astrocytes in the optic nerve head to a subtle injury induced by a brief, mild elevation of the intraocular pressure. Astrocytes demonstrated reactive remodeling showing hypertrophy, process retraction and simplification of their shape. We used microarray to indentify differentially expressed genes and to investigate the molecular mechanisms of astrogliosis in response to this subtle injury. Six- to eight-week old C57Bl/6 male mice were used in this experiment. One eye underwent an elevation in intraocular pressure to 30 mmHg for 1 hour and then allowed to recover for 3 days. The contralateral eye served as a control. Due to the small tissue size of the mouse optic nerve head, two optic nerve heads were pooled together for each microarray chip. We used 10 mice to generate five biological replicates for each condition.
Project description:Previous studies indicated that activation of glial cells and inflammatory responses are triggering factors of glaucomatous optic neuropathy. In particular, neurotoxic reactive astrocytes have been found to play a significant role in retinal ganglion cell damage. Furthermore, research showed that activation of glial cells is not dependent on retinal ganglion cell injury, but rather a direct response to pathological elevation of intraocular pressure. However, the molecular mechanism by which elevated intraocular pressure triggers glial activation through mechanical forces remains unknown. By spatial transcriptome sequencing, our study revealed that the neurotoxic astrocyte would rapidly be reactivated in the optic nerve head under elevated intraocular pressure in vivo.
Project description:The optic nerve is an important tissue in glaucoma and the unmyelinated nerve head region remains an important site of many early neurodegenerative changes. In humans and mice, astrocytes constitute the major glial cell type in the region, and in glaucoma they become reactive, influencing the optic nerve head (ONH) microenvironment and disease outcome. To determine the response of ONH astrocytes in glaucoma, we studied their transcriptional response to an elevation in intraocular pressure (IOP) induced by the microbead occlusion model. We also assessed the response of astrocytes in the more distal myelinated optic nerve proper (ONP). In this experimental model, astrocytes of the optic nerve exhibited a region-specific and temporally distinct response: ONH astrocytes showed very few early transcriptional changes and ONP astrocytes demonstrated substantially larger changes over the course of the experiment.
Project description:Reactive astrocytes are typically studied in models that cause irreversible mechanical damage to axons, neuronal cell bodies, and glia. We evaluated the response of astrocytes in the optic nerve head to a subtle injury induced by a brief, mild elevation of the intraocular pressure. Astrocytes demonstrated reactive remodeling showing hypertrophy, process retraction and simplification of their shape. We used microarray to indentify differentially expressed genes and to investigate the molecular mechanisms of astrogliosis in response to this subtle injury.
Project description:A major risk factor for glaucomatous optic neuropathy is the level of intraocular pressure (IOP), which can lead to retinal ganglion cell axon injury and cell death. The optic nerve has a rostral unmyelinated portion at the optic nerve head followed by a caudal myelinated region. The unmyelinated region is differentially susceptible to IOP-induced damage in rodent models and in human glaucoma. While several studies have analyzed gene expression changes in the mouse optic nerve following optic nerve injury, few were designed to consider the regional gene expression differences that exist between these distinct areas. We performed bulk RNA-sequencing on the retina and on separately micro-dissected unmyelinated and myelinated optic nerve regions from naïve C57BL/6 mice, mice after optic nerve crush, and mice with microbead-induced experimental glaucoma (total = 36). Gene expression patterns in the naïve unmyelinated optic nerve showed significant enrichment of the Wnt, Hippo, PI3K-Akt, and transforming growth factor β pathways, as well as extracellular matrix–receptor and cell membrane signaling pathways, compared to the myelinated optic nerve and retina. Gene expression changes induced by both injuries were more extensive in the myelinated optic nerve than the unmyelinated region, and greater after nerve crush than glaucoma. Changes present three and fourteen days after injury largely subsided by six weeks. Gene markers of reactive astrocytes did not consistently differ between injury states. Overall, the transcriptomic phenotype of the mouse unmyelinated optic nerve was significantly different from immediately adjacent tissues, likely dominated by expression in astrocytes, whose junctional complexes are inherently important in responding to IOP elevation.
Project description:The mechanical effect of raised intraocular pressure is a recognised stimulus for optic neuropathy in primary open angle glaucoma (POAG). Characteristic extra-cellular matrix (ECM) remodelling accompanies axonal damage in the lamina cribrosa (LC) of the optic nerve head in POAG. Glial cells in the lamina cribrosa may play a role in this process but the precise cellular responses to mechanical forces in this region are unknown. The authors examined global gene expression profiles in lamina cribrosa cells exposed to cyclical mechanical stretch, with an emphasis on ECM genes. Experiment Overall Design: n=3 stretch and static control experiments. Experiment Overall Design: RNA pooled from each experiment and hybridised to individual experiment and control arrays.
Project description:The mechanical effect of raised intraocular pressure is a recognised stimulus for optic neuropathy in primary open angle glaucoma (POAG). Characteristic extra-cellular matrix (ECM) remodelling accompanies axonal damage in the lamina cribrosa (LC) of the optic nerve head in POAG. Glial cells in the lamina cribrosa may play a role in this process but the precise cellular responses to mechanical forces in this region are unknown. The authors examined global gene expression profiles in lamina cribrosa cells exposed to cyclical mechanical stretch, with an emphasis on ECM genes. Keywords: microarray, ECM, glaucoma, mechanical stretch, lamina cribrosa
Project description:The death of retinal ganglion cells(RGC) after the damage on optic nerve as a result of high intraocular pressure is the main reason of the irreversible blindness in glaucoma patients ,and mammals have very limited ability of maintaining the RGCs after optic nerve injury.Zebrafish,however,possess the ability of keep most RGCs from death after optic nerve injury. The purpose of this study is to determine which gene or pathway mediate the RGC survival mechanism underlying.It is observed JAK/STAT signaling pathway as well as the innate immune response is activated after optic nerve injury(in this study,optic nerve transection).Pharmacological inhibition of JAK/STAT by intravitreal(IV) injection of JAK inhibitor,P6,induced the reduction of RGC survival while both local and systemic immune suppressor application result in the rescue of RGC survival.Moreover,phospho-STAT3(pSTAT3),which is an evidence of STAT3 activation,demonstrated elevation of expression level after ONT,and the trend of pSTAT3 expression change is consistent with the RGC survival rate change .JAK inhibition reduced pSTAT3 expression level and immune suppressor application elevated the pSTAT3 expression level on RGCs. In summary,these data suggested JAK/STAT signaling pathway crosstalk with innate immune response create a dynamic balance in the mechanism of RGC survival.Interestingly,innate immune response which was used to be considered promoting tissue repair in other studies,proved to be suppressing RGC survival in this study.These data could be used as reference for future direction of neuroprotection in glaucoma treatment.
Project description:This SuperSeries is composed of the following subset Series:; GSE9939: Gene expression data on human optic nerve head astrocytes in normal Caucasian and African americans; GSE9944: Gene expression data on human optic nerve head astrocytes in Caucasian and African americans with or without glaucoma Experiment Overall Design: Refer to individual Series